state of the environment assessment for the … · mamaku ranges, including all relevant data held...

Crown Copyright: Department of Conservation Te Papa Atawhai,

Environment Bay of Plenty, Environment Waikato (2010).

STATE OF THE ENVIRONMENT

ASSESSMENT FOR THE CATCHMENTS

OF THE KAIMAI RANGE AND

NORTHERN MAMAKU PLATEAU

FEBRUARY 2010

Report No. 2075

Prepared by Wildland Consultants Ltd for: DEPARTMENT OF CONSERVATION P.O. BOX 9003 TAURANGA 3142 ENVIRONMENT BAY OF PLENTY P.O. BOX 364 WHAKATANE 3158 ENVIRONMENT WAIKATO P.O. BOX 4010 HAMILTON 3247

© Crown Copyright 2010 1 Contract Report No. 2075

CONTENTS

CONTENTS 1

ACKNOWLEDGMENTS 5

1. PROJECT OUTLINE 6

2. EXECUTIVE SUMMARY 8

3. INTRODUCTION 15

3.1 Catchment description 15

3.2 History of land use 17

3.3 Present functions and uses 21

4. OVERVIEW AND CONTEXT 21

4.1 Land tenure and status 21

4.2 Geology and landforms 23

4.3 Climate 30

4.4 Land use and erosion 31

4.4.1 Land use capability 32

4.4.2 LUC and land cover 33

4.4.3 Past and present erosion 36

4.5 Water quality 38

4.5.1 Waihou River catchment 38

4.5.2 Tauranga Harbour catchment 39

4.5.3 Stream characteristics 40

4.6 Resource management roles and responsibilities 44

4.6.1 Department of Conservation 44

4.6.2 Regional Authorities: Environment Waikato and Environment Bay of Plenty 44

4.6.3 Territorial Authorities: District Councils 45

4.6.4 Iwi 45

4.7 Ecological context 45

4.8 Vegetation 50

4.8.1 Land cover 51

4.8.2 Indigenous forest - broad pattern 53

4.8.3 Indigenous forest on the range and plateaus 56

4.8.4 Other vegetation and habitat inventories 58

4.9 Flora 59

4.9.1 Weed Impacts 61

4.10 Indigenous forest ecology 63

4.11 Indigenous fauna 66

4.11.1 Avifauna - historic 66

4.11.2 Avifauna - current 68

4.11.3 Fish 74

4.11.4 Terrestrial invertebrates 77

4.11.5 Aquatic invertebrates 79

4.11.6 Herpetofauna 80


4.11.7 Bats 83

4.12 Introduced mammals 84

4.13 Recreation 87

5. CURRENT MANAGEMENT 90

5.1 Department of Conservation 90

5.2 Environment Waikato 112

5.3 Environment Bay of Plenty 116

5.4 Other management and monitoring 118

5.5 Care groups 120

6. CATCHMENT SUMMARIES 123

6.1 Waihou catchments 123

6.1.1 Waihi 123

6.1.2 Paeroa 124

6.1.3 Te Aroha 124

6.1.4 Middle Waihou 125

6.1.5 Upper Waihou 126

6.2 Tauranga-Bay of Plenty catchments 126

6.2.1 Waiau 126

6.2.2 Tuapiro 127

6.2.3 Uretara 127

6.2.4 Rereatukahia 128

6.2.5 Aongatete 129

6.2.6 Te Puna 130

6.2.7 Wairoa 130

6.2.8 Omanawa 131

6.2.9 Waimapu 132

6.2.10 Otawa 133

7. KEY FINDINGS AND CONCLUSIONS 134

7.1 Geology and landforms 134

7.2 Catchments 134

7.3 Land cover 134

7.4 Human influences 135

7.5 Soil and water conservation 135

7.6 Climatic influences 135

7.7 Diversity of ecosystem types 135

7.8 Vegetation and floral diversity 136

7.9 Ecological values of vegetation 136

7.10 Indigenous avifauna 137

7.11 Bats, lizards, and fish 138

7.12 Vegetation monitoring 139

7.13 Concluding statement 143


REFERENCES AND SELECTED BIBLIOGRAPHY 146

APPENDICES 1. Catchment-based ecological overviews 190

- Waihi 191

- Paeroa 204

- Te Aroha 216

- Middle Waihou 229

- Upper Waihou 241

- Waiau 255

- Tuapiro 266

- Uretara 278

- Rereatukahia 290

- Aongatete 302

- Te Puna 314

- Wairoa 327

- Omanawa 341

- Waimapu 354

- Otawa 367

2. Water quality indicators 380

3. Land use capability 390

4. Land environment classifications for sub-catchments 402

5. Landcover and stream gradients within sub-catchments 405

6. Forest classes within sub-catchments 409

7. Care group summary 412

8. Vegetation types represented in ecological reserves 417

9. Photographs of selected parts of project area 425

FIGURES 1. Location of project area 3 2a. Department of Conservation (DOC) protected areas 24 2b. All protected areas 25 3. Geology 27 4. Land Use Capability (LUC) classes in the Waihou and Tauranga catchments (pie graph) 33 5. LUC classes in the Kaimai-Mamaku catchments (map) 34 6. LUC and land cover within the Waihou and Tauranga catchments (bar graph) 35 7. Landcover and stream pattern and gradients 43 8. Land environment threat classifications and ecological district boundaries 48 9. Indigenous forest pattern 52 10. Vascular plant lists and threatened plant records 62 11. DOC database weed records 65 12a. OSNZ Atlas records 1969-1979 for common forest birds 70


12b. OSNZ Atlas records 1999-2004 for common forest birds 71 12c. Kiwi records and OSNZ records for less common forest birds 72 13. Indigenous fish records 76 14. Koi carp sites in Tauranga catchment 79 15. Lizard and frog records 82 16. DOC goat and possum control operations 93 17. DOC goat kills 2004-2007 94 18. DOC goat kills 2008-2009 95 19. DOC management zones at Opuiaki 98 20. DOC bait station and trap line layout at Opuiaki 99 21. DOC pest control treatment area at Mokaihaha 101 22. Overall vegetation monitoring network 104 23. DOC vegetation monitoring network in the northern Kaimai Range 105 24. DOC vegetation monitoring network in the southern Kaimai Range 106 25. DOC vegetation monitoring network at Opuiaki 107 26. DOC vegetation monitoring network in the Otanewainuku-Otawa Range 108 27. New Zealand Forest Service transects for faecal pellet assessments 112 28. DOC track and hut network in the Kaimai-Mamaku project area 114 29. Otanewainuku Kiwi Trust pest control operational area 120 30. Aongatete Forest Restoration Trust pest control operational area 123 31. Care groups 124 PROJECT TEAM William Shaw - Report author. Matt Renner - Information compilation, report author. Richard Gillies - Fauna, report author. Astrid van Meeuwen-Dijkgraaf - GIS analysis. Federico Mazzieri - GIS mapping and analysis. Marlé Rossouw - GIS mapping. Scott Thomas - Bibliogaphy. Reviewed and approved for release by:

_______________________ W.B. Shaw Director/Principal Ecologist Wildland Consultants Ltd


ACKNOWLEDGMENTS

Andrew Baucke (DOC) - project liaison.

Brad Angus (DOC) - information on DOC pest control and monitoring operations.

Brendon Christensen (DOC) - information on DOC management activities.

Carlton Bidois (Pirirakau) - Pirirakau perspective.

Chris Clarke (DOC) - project liaison.

Chris Dench (Tauranga Environment Centre) - care group activity within Tauranga City.

Dave Wills - information on Otanewainuku Kiwi Trust operations.

Gareth Evans (EBOP) - LUC analysis.

Jeanie McInnes (EW).

John Heaphy (DOC) - information on short-tailed bats.

John Simmons (EW).

Kate Akers (NZ Landcare Trust).

Katrina Knill (DOC) - project liaison.

Keith Owen (DOC) - information on short-tailed bats.

Margaret Honey (Wildlands) - word processing.

Mark Bougen (Western Bay of Plenty District Council) - information on care groups.

Matt Bloxham (EBOP) - information on stream monitoring.

Paul Cashmore (DOC) - information on threatened plants, and vegetation condition.

Peter Maddison (Forest and Bird) - for sharing Forest and Bird‘s vision for the project

area.

Rien van der Wetteringh (EW) - for information on Waihou Management Scheme and

providing the LUC analysis.

Rob McGowan (DOC) - for information on Nga Whenua Rahui activities.

Robyn Skelton (EBOP) - project liaison.

Roz Perry (EBOP) - for information on care groups and pest plants.

Sarah Crump (DOC) - weed records from DOC database.

Tom Pyatt (DOC) - supplying various GIS layers.

Photographs Cover - Wairere Falls, Department of Conservation

Plates 1-4 - Wildland Consultants Ltd

Plate 5 - Environment Waikato

Appendix 9 - Wildland Consultants Ltd


1. PROJECT OUTLINE

The Department of Conservation, Environment Bay of Plenty, and Environment

Waikato have formed a working party to cooperatively explore options for a joint

planning and management approach for the Kaimai-Mamaku Ranges, in order to

protect and enhance the significant catchment, conservation, and recreational values

that this area provides for the region. The working party acknowledges the need to

work with local communities and stakeholders in planning and implementing such a

joint management approach and as a first step have begun to collect information from

stakeholders and interested parties throughout the community, regarding what they

want from the Kaimai-Mamaku Forest Park and the management actions they believe

are required. The working party also recognised the need to report on the

environmental state of the ranges and commissioned Wildland Consultants Ltd to

deliver this output.

The project objective is to:

“Provide a comprehensive report on the environmental state of the Kaimai

Range.”

The project scope includes:

Review and reference all relevant environmental data/information on the Kaimai

Mamaku Ranges, including all relevant data held by the Department of

Conservation, Environment Waikato, and Environment Bay of Plenty.

Summarise and report on key findings and environmental trends.

Identify and prioritise threats, risks, pressures, and impacts.

Review past and current management and land use practices on public and private

land, and measure these against predicted environmental state of health trends for

the next 20 years.

Identify any data deficiencies or monitoring gaps.

The project excludes specific environmental monitoring services.

For the purpose of this project the Kaimai-Mamaku project area includes all stream

catchments that flow from the Kaimai Mamaku Ranges into the Tauranga Harbour

and Waihou River (refer to Figure 1). It also encompasses the northern catchments of

the Otanewainuku-Otawa Range that extend north-east from the Mamaku Plateau.

The total project area is more than 240,000 ha, encompassing 15 adjoining sub-

catchments that flow westwards into the Waihou River (5 sub-catchments) and

eastwards to the Tauranga Harbour (10 sub-catchments), as summarised in Table 1.

The northern boundary is the Ohinemuri River, while the southern boundary is

defined by the catchment of the Otawa Stream (Tauranga Harbour catchment) and

Oraka Stream (Waihou River); the western boundary defined by the course of the

Waihou River; and the eastern boundary by the line of mean high water spring as it

follows the oceanic and harbour coastlines of the Bay of Plenty.


Table 1: Sub-catchments and areas (in hectares) within the Kaimai-Mamaku Project Area.

Waihou Sub-Catchments Area (ha) Tauranga Sub-Catchments Area (ha)

Waihi 16,625 Waiau 5,885

Paeroa 10,379 Tuapiro 6,622

Te Aroha 3,055 Uretara 5,336

Middle Waihou 15,381 Rereatukahia 6,173

Upper Waihou 72,986 Aongatete 12,543

Te Puna 8,630

Wairoa 36,930

Omanawa 17,330

Waimapu 13,029

Otawa 9,862

Total 118,426 Total 122,340

Source: GIS analysis undertaken by Wildland Consultants Ltd.

The Tauranga Harbour sub-catchments (122,340 ha) are mainly individual catchments

originating on the Kaimai-Mamaku ranges with single discharge points into the

harbour, while the Waihou sub-catchments (118,426 ha) are groups of smaller

tributary catchments with similar characteristics (stream type, geology, topography)

generally running parallel to each other and discharging into the Waihou and

Ohinemuri Rivers at various points.

2. EXECUTIVE SUMMARY

Background

The Department of Conservation, Environment Bay of Plenty, and Environment

Waikato have formed a working party to cooperatively explore options for a joint

planning and management approach for the Kaimai-Mamaku Ranges, in order to

protect and enhance the significant catchment, conservation, and recreational values

that this area provides. The objective for this project was to ―provide a

comprehensive report on the environmental state of the Kaimai Range‖, including all

stream catchments that flow from the Kaimai-Mamaku Ranges into Tauranga Harbour

and the Waihou River, also encompassing the northern catchments of the

Otanewainuku-Otawa Range that extend north-east from the Mamaku Plateau.

Project Area

The project area encompasses a distinctive suite of prominent landforms and the

Kaimai Range, in particular, is very prominent from the Waikato and the Bay of

Plenty, and is highly valued by the people of both regions. With the exception of the

plains and downlands on the western and eastern sides of the range and plateaus, these

landforms are largely of volcanic origins, with fault uplift resulting in the large

western scarp rising above the Waikato Basin. North-south, the project area spans

almost 90 km, and c.40 km west-east at its widest point, encompassing more than

240,000 ha, in 15 sub-catchments. Five of these sub-catchments - Waihi, Paeroa,

Te Aroha, Middle Waihou, Upper Waihou - flow into the Waihou River and drain the

northern part of the Kaimai Range, the steep western flanks of the range, and the


western parts of the northern Mamaku Plateau. The other ten - Waiau, Tuapiro,

Uretara, Rereatukahia, Aongatete, Te Puna, Wairoa, Omanawa, Waimapu, and

Otawa - drain from the northern hill country near Waihi Beach, the eastern flanks of

the Kaimai Range, the Whakamarama Plateau, the north-eastern parts of the northern

Mamaku Plateau, and the Otawa-Otanewainuku hills to the Tauranga Harbour. The

Tauranga Harbour sub-catchments (122,340 ha) are mainly individual catchments

originating in the Kaimai-Mamaku ranges, with single discharge points into the

harbour, while the Waihou sub-catchments (118,426 ha) are groups of smaller

tributary catchments with similar characteristics (stream type, geology, topography)

that discharge into the Waihou and Ohinemuri Rivers.

Land Use Capability

There is a long history of land use, including extensive forest clearance by Māori

burning, followed by further clearance and modification for farming, logging, and

mining. People also actively introduced many exotic animals and plants, some of

which have had dramatic effects on indigenous vegetation, flora, and fauna. The

steeply uplifted nature of the Kaimai Range and the steeply-incised character of

streams draining the Range and plateaus means that the forested headwaters have very

high values for water and soil conservation. More than half of the project area is hill

country in Land Use Capability (LUC) Classes 6, 7, and 8 (Waihou catchment 58%;

Tauranga Harbour catchment 64%). From a catchment management perspective, these

are the classes of land at risk of erosion and damaging run-off if not managed

appropriately. Management of existing forest cover is therefore important to minimise

erosion and run-off. Class 8 land is not suitable for productive use while

production/protection forestry or other erosion control measures may be required on

Class 6 and 7 farmland. It should also be noted that activities such as cultivation,

earthworks, and stock management on LUC Classes 1-4, particularly adjacent to

waterways, also require appropriate management with regard to potential impacts on

water quality. Particularly steep catchments are the Te Aroha sub-catchment in the

Waihou (75% hill country) and Wairoa (76%) in the Tauranga Harbour catchment.

Approximately two-thirds of the hill country has a cover of forest and scrub (Waihou

catchment 70% and Tauranga Harbour catchment 66%), although some sub-

catchments such as Paeroa (33%) in the Waihou catchment and Waiau (56%),

Te Puna (44%), Waimapu (50%) and Otawa (48%) in the Tauranga catchment have a

lower proportion of forest and scrub cover on steeper slopes. A considerable

proportion of the hill country in these sub-catchments is used for farming.

Catchment Management, Flood Protection and Water Quality

Patterns of land tenure and land use on the western and eastern sides of the Kaimai

Range and Mamaku Plateau are quite different, with mainly dairy farming and

plantation forest on the western side and many lifestyle blocks and orchards on the

eastern side, with fewer larger farms. As land clearance progressed in the upper

western (Waihou) catchments, erosion also started to become a significant problem.

Large quantities of soil, gravel, and other debris were regularly washed off the steep

Kaimai Range, infilling channels, and were deposited on farm land and in urban areas,

damaging property and infrastructure. Severe storms and flooding required stop-

banking to protect farm land and urban areas. The need for upper catchment

protection, together with improved flood protection, culminated in the Waihou Valley


Scheme, integrating upper and lower catchment works. Access to high quality water

resources is particularly important as many streams provide water for settlements,

rural dwellers, and domestic stock. There is a general pattern of decreasing water

quality in the Waihou with increasing distance down the catchment, and a similar

pattern is evident in the lower reaches of the Tauranga catchments (the regional

councils have well-developed water quality monitoring networks on both sides of the

range). Sediment losses into streams and estuaries is also an ongoing concern, and

steep gradient streams in pasture are a recognised sediment source on the eastern side

of the range. There is a high level of community concern in the lower catchments, in

particular regarding erosion, sedimentation of receiving streams, rivers, and the

Tauranga Harbour; and deteriorating water quality moving downstream, as shown by

the proliferation of care groups, particularly in the lower catchments. Environment

Waikato and Environment Bay of Plenty have environmental programmes in place to

assist private landowners to protect biodiversity and water and soil functions.

Land Tenure and Status

The Kaimai Range has had a long history of strong public interest, having previously

been the subject of a campaign, in the 1970-1980s, to establish a National Park in this

area. The Kaimai-Mamaku Forest Park (37,141 ha) was initially established largely

for soil and water conservation purposes, although the Forest Park has also been

subject to considerable ecological evaluation, with representative segments gazetted

as ‗Ecological Areas‘, which are located throughout the forest tract. Many other

protected areas are present within the project area, including QEII covenants,

Nga Whenua Rahui kawenata, and covenants established as a condition of resource

consents for land subdivision. Although a large proportion of the forest-covered

range and plateaus is in public ownership, there are also significant areas of

indigenous forest in private ownership, which have significant soil and water

functions as well as biodiversity values. Various statutory plans contain controls on

vegetation clearance and riparian protection. Crown conservation lands are primarily

on steeper, higher altitude lands associated with the Kaimai Range and the Mamaku

plateau, and the greater part of the main Kaimai Range is administered by the

Department of Conservation, although significant areas of freehold and Māori lands

are intermixed with Department of Conservation lands along the southern Kaimai

Range, particularly on the Mamaku Plateau.

Extent of Indigenous Vegetation

The total area of indigenous vegetation is nearly 89,000 ha, of which c.70% is

formally protected. Much of the forested part of the project area is managed by the

Department of Conservation but there are also large areas of indigenous vegetation

(more than 25,000 ha) in private and Māori ownership. Most indigenous vegetation is

located in the upper catchments, on steeper country, and on the extensive plateaus in

the south, although large parts of the Mamaku Plateau have been converted to exotic

plantation forest. In the middle reaches of the catchments there are many smaller

remnants of indigenous vegetation, including many that extend along streams to the

east. Relatively little indigenous vegetation remains in the lower altitude parts of

most of the 15 sub-catchments, with large swathes of landscape now classed as

acutely threatened (<10% indigenous cover remaining) or chronically threatened

(<20% remaining), with the limited remnants often degraded by grazing or weed


invasion. Various pest animal species are present throughout, often having pervasive

effects. Increasing numbers of privately-owned remnants are legally protected, and

subject to active restoration management.

Indigenous Forest Pattern

At lower levels and closer to the coast, coastal ecosystems are prevalent, with

pohutukawa prominent. Semi-coastal forest, with species such as kohekohe and puriri,

occurs along the eastern flanks of the range, with a similar pattern evident, at lower

levels, on the western side of the range. Podocarp/tawa and tawa-dominant forest is

predominant on lower and mid-slopes, and on the plateaus. In the north, however,

there are complex mixtures of tawa, beeches, and kauri, with local kauri stands on

both sides of the range (many of which have been logged). Red beech-silver beech

and silver beech forest occurs on some of the higher ridges, with upland bog forest on

flatter terrain at higher altitude. Extensive volcanic rock outcrops (e.g. Wahine Rock,

Kakarahi) on the main Kaimai Range provide significant habitats for a diverse range

of plants of open sites. The effects of climate on vegetation and habitats across the

project area results from a complex set of interactions with altitude, vegetation

composition and land use, distance from the coast, and landforms and soils. A strong

climatic influence is evident on the highest parts of the range where a cloud or fog cap

is a characteristic feature for nearly two-thirds of the year. This feature, combined

with sporadic extreme droughts, means that these higher altitude forests, which have

developed to suit wet climatic conditions, are vulnerable to drought-induced dieback.

Drought events in the early and middle parts of the 20th

century triggered widespread

dieback of indigenous vegetation in ‗cloud forest‘, and these effects are still very

evident along the highest ridges today, resulting in the ―scruffy‖ vegetation that is

present in these areas.

Indigenous Biodiversity

The high degree of ecological diversity within the project area is a reflection of the

considerable diversity of basal geology, landforms, and altitude, combined with

distributional limits for various key species. Geologically, the northern Kaimai is

distinctly different from the central Kaimai and the southern plateaus. Ecologically,

the northern Kaimai Range has strong affinities with the Coromandel, while the

Mamaku plateau is characteristic of the central North Island. The distinctive

transition zone, in the central part of the Range, has affinities to both, including

various northern and southern distributional limits. Thus, the Range is a key

connection and gradation between the forests of the central North Island and the

Coromandel. This ecological transition zone includes northern limits for silver beech,

kamahi, and pink pine, and southern limits for Coprosma dodonaefolia and towai.

Kauri forest reaches its southern limit on the eastern side of the North Island within

the project area. The range of ecosystem diversity is reflected in the formal

recognition of seven separate gazetted Ecological Areas and a Forest Sanctuary across

the north-south extent of the project area. The northern section of the range, from

Karangahake Gorge to the Ngatamahinerua Ridge and the Kaimai tunnel area, just

south of Gordon, can be considered to be ―unique‖, on the basis that this area is

geologically distinct from the main Coromandel Range to the north and the Kaimai

Range to the south, it rises to a higher altitude than either and has a very varied

terrain, and it contains a multitude of complex forest types. The degree of diversity


across the project area, on a wider landscape scale, is illustrated by subdivision of the

project area into eight ecological districts, within four ecological regions. The Kaimai

Range and plateau environments, in spite of the presence of pest animals, still have

very important biodiversity values, with large areas of the tract ranked as having

‗Exceptional‘ botanical conservation values. The diversity of ecosystem types

represented across a wide altitudinal range, from coastal to montane, means that there

is a great diversity of vascular plants, with 500-600 indigenous taxa present, including

at least 30 threatened or ‗at risk‘ species, and another six taxa considered to be

uncommon on a regional basis. The fauna complement is also very significant, with a

diverse range of threatened avifauna, including kokako, kiwi, kākā, falcon, and long-

tailed cuckoo. A now typical suite of common forest birds is present throughout.

Falcon occur throughout but kākā are only itinerant visitors over much of the tract,

other than the northern Mamaku Plateau. Long-tailed bats are probably present

throughout indigenous forest associated with the main forest tract, but short-tailed

bats are only known from Opuiaki and Mokaihaha. Records of common lizards are

present throughout. Hochstetter‘s frog occurs at Otawa (just outside of the project

area) and in the northern Kaimai Range. A diverse complement of invertebrates is

present, including rare species such as the Te Aroha stag beetle. There are still

significant populations of indigenous fish in streams, including some threatened

species. Upper catchments provide high quality fish habitats but it is evident that the

lower reaches of most waterways are heavily modified and are under considerable

pressure from catchment land uses. Ongoing connectivity to the sea is critical for

migratory indigenous species, and downstream habitat quality is important for those

species that utilise lowland habitats, either at key stages of their life cycles or on an

ongoing basis. It is clear, from the data available, that there is a concentration of

remnant threatened species in the south. It also appears that there is a more diverse

complement of common species in the northern Kaimai than there is in the central

part of the Range. This may be related to the relative extent and diversity of habitats

available in different parts of the project area.

Pest Animals

There is a ubiquitous suite of introduced pest animals present across the entire tract

and, where not under active management, these have had, and continue to have,

significant negative effects on indigenous vegetation and fauna, resulting in the steady

decline and ongoing loss of key elements from remaining indigenous ecosystems.

Introduced predators such as mustelids, rats, cats, hedgehogs, mice, and pest

invertebrates (e.g. wasps) have taken a heavy toll on terrestrial indigenous fauna,

especially birds, lizards, and invertebrates. These predators are ubiquitous across the

entire tract. Limited fauna monitoring data is available, and pest control to protect

indigenous avifauna is undertaken at a limited number of sites. Pest fish (koi carp)

are present in some eastern catchments but are subject to an eradication programme.

It is also evident that elements of the vegetation have been severely affected by

introduced browsing animals such as goats and possums, with deer also present and

increasing in parts of the central Kaimai Range. These animals have altered canopy

composition and condition, as well as understorey composition and structure and

regeneration sequences. Nevertheless, there are still parts of the northern Mamaku

Plateau - such as Opuiaki - that have not been heavily impacted by introduced

browsing animals and forest structure is relatively intact.


Pest Animal Control

Goat control has been implemented widely for many decades. Currently, this is

strongly focussed on the northern Kaimai, but has previously involved considerable

monitoring and hunting responses in central and southern Kaimai. Goat control has

also been undertaken at Orokawa Bay, along with control of feral pigs and possums.

Possum control has been undertaken by the Department of Conservation in the

Waiorongomai Valley, at Opuiaki (5,600 ha), at Mokaihaha (1,130 ha), and at

Otanewainuku (900 ha), and Otawa (adjacent to the project area). Control of

mustelids and ship rats has also been undertaken by the Department of Conservation

at Opuiaki, and of ship rats only at Mokaihaha. Other possum control has been

undertaken at Whakamarama and Otanewainuku-Otawa (adjacent to the project area).

Integrated pest control is also being implemented on conservation land and Māori

land at Whakamarama, and at Mokaihaha, as part of a pest control research project

undertaken by Landcare Research. There are now also two community-based trusts

undertaking intensive pest control in forested areas (at Otanewainuku and Aongatete)

and a care group doing the same (at Puketoki).

Pest Plants

The diversity of habitats, combined with the high degree of fragmentation, urban

settlement and rural subdivision, has led to a great proliferation of pest plants and this

problem will not diminish over time as there is a considerable lag time for further

expansion of species spreading by wind, birds, and garden waste dumping. The

regional councils and DOC all have well-developed surveillance, recording, and

control programmes in place, but this will require ongoing commitment.

Vegetation Monitoring

The Department of Conservation has vegetation monitoring in place in various parts

of the wider tract, with a strong focus on the northern Kaimai. In the north, this

monitoring includes a network of rata view sites, permanent 20 20 m vegetation

plots, foliar browse lines, and exclosures. In the central and southern zones, the main

focus is on foliar browse assessments. Most catchments have some vegetation

monitoring infrastructure, and those that don‘t, often have comparable monitoring

sites in adjacent catchments in similar vegetation types. The notable exception is

upland forest in the Te Hunga and Waiteariki Ecological Areas. While the monitoring

data that is available is somewhat patchy in terms of geographic spread, there is

enough information available to formulate a picture of the current state of the

vegetation. Post-2000 monitoring assessments in various parts of the project area

have shown declines in the canopy condition of northern rata in the northern Kaimai,

but have indicated that other possum-preferred species were in moderate to good

condition there. In the southern Kaimai, monitoring has indicated kamahi to be in

poor condition, but other species have improved in condition. This ‗picture‘ is related

to the pattern and history of possum control, and a similar ‗picture‘ is evident in

relation to the effects of deer and goats. Current monitoring data for feral red deer

and possums appears to be lacking. Other biodiversity monitoring, in the lower

Tauranga catchments, is being undertaken by Western Bay of Plenty District Council,

Environment Bay of Plenty, and Tauranga City Council.


Forest Health and Threats

There is wide concern that the forests of the Range not currently under intensive

management are on the verge of experiencing collapse, and that the indigenous

fauna - vertebrates and invertebrates - have suffered catastrophic population collapses.

It is, however, readily evident that forests on the northern Mamaku Plateau are in

relatively good condition, especially areas where possums are being managed and

where more intensive integrated pest management has occurred in the recent past. It

is also evident that forests of the northern Kaimai are in reasonable condition and that

adequate levels of vegetation monitoring are in place to detect changes. The northern

Kaimai is also under active management for goat control, and possum control has

been implemented over one block where rata condition is of concern. Tawa-dominant

forest is predominant on lower and mid-slopes on the central Range, with a

recognised deer population. These forests now have limited vulnerability to browse

impacts, subject to pest populations not attaining high levels. Upland forest on the

Range appears to be in a poor state, but this is due primarily to the effects of drought-

related forest dieback, triggered by two key drought events in the early and mid-

20th

Century. Browsing animals do, however, play an important role in regeneration

at dieback sites, and possums are also a known factor in kaikawaka decline. There

may be a need to increase monitoring (and management) effort in upland forests on

the highest ridges, and this needs further evaluation. Indigenous fauna, especially

birds, are of particular concern, but the major declines and local extinctions due to

predation have already occurred, as for extensive areas of most mainland habitats, and

it is now a matter of determining where management effort should be directed. There

is probably a need for further targeted surveys of key species, to underpin selection of

further intensive management sites, although this is only one factor that should be

taken into account in the evaluation of priorities for ecosystem management.

Monitoring (and management) within the ‗core‘ Kaimai-Mamaku tract is somewhat

patchy and has become focussed on particular locations and there would be merit in

taking a more holistic approach to future management. There is enough monitoring

information to indicate that more active management is required in representative

parts of the upper catchments (in addition to the areas already subject to intensive

management), to halt and reverse the decline of indigenous biodiversity. There is also

sufficient information available to indicate the types of recovery (and recovery

trajectories) that can be expected if a wider programme of active management is put

in place. The previous delineation of key representative vegetation sequences and

special features in Ecological Areas and a Forest Sanctuary needs greater recognition.

These areas are currently receiving active management in the northern Kaimai (goat

control) and northern Mamaku (recent control of possums, stoats, rats), but need more

emphasis in the central and southern Kaimai Range.

Community Interest and Involvement

The Waikato and western Bay of Plenty are major population centres, with intensive

land subdivision occurring in the western Bay of Plenty. Levels of increased use in

adjacent lowlands is being reflected by increased use (and related interest in

management regimes) in the forests along the range, with c.200,000 annual visitors.

As well as walking/tramping, there is significant interest in historic interpretation,

hunting, mountain biking, 4WD, whitewater kayaking, and trout fishing. There is


now considerable pressure from the wider community for increased active

management in the wider forested tract, as well as throughout much of the lower

sections of the 15 sub-catchments. Ecological restoration is a strong focus in these

degraded environments, as shown by the more than 50 community-based ecological

care groups operating (with only a few exceptions), mainly in the lower to middle

reaches of the Tauranga catchments. These care groups are well aware of the

importance of sound ecological management and sustainable rural land use for

receiving environments such as Tauranga Harbour and the Waihou River and Firth of

Thames.

Conclusion

With growing population pressure, particular in the Bay of Plenty and changing land

uses such as advancing urban and rural interfaces but also agricultural intensification

within the Kaimai-Mamaku catchments, conservation efforts need to strategically

align with and contribute to social and economic policies. This can only realistically

be achieved by proactive long-term engagement with communities within and

adjacent to the project area. It is also obvious that it is beyond the capabilities of a

single agency, an agency collective, or even the combined efforts of agencies and the

wider community, to achieve ecosystem recovery uniformly across the project area. It

will be necessary to pick ―winners‖, in terms of representative swathes of indigenous

forest and selected catchments, in which to implement additional restoration

management. It will also be necessary to expand and integrate the monitoring

network, to be able to continue to evaluate condition and trend within these systems,

and to report on achievements over time. If these matters are addressed, it is feasible

to sustain and restore the indigenous biodiversity of the Kaimai-Mamaku into the

future.

3. INTRODUCTION

3.1 Catchment description

The Kaimai Range and Mamaku Plateau are prominent volcanic-origin landforms

dominating landscapes of the eastern Waikato and western Bay of Plenty.

West of the Kaimai Range and Mamaku Plateau, catchments flow into the Waihou

River. The upper Waihou River and its tributaries are largely spring fed, as water

from the Mamaku plateau infiltrates into and percolates through thick ignimbrite

sheets before emerging in springs. Water in the streams along the Kaimai Range is

mainly sourced from run off. The Waihou, as it increases in flow from run off, flows

down the Hauraki Rift and into the Firth of Thames, which is part of the Hauraki Gulf

Maritime Park.

Rivers and streams flowing from the Kaimai Range are typically heavily-incised, with

steep drops and valley sides. To the east (see Plates 1 and 2), catchments within the

project area all flow into the Bay of Plenty. Catchments to the east and west of the

Kaimai Range have similar characters, being bouldery with relatively steep falls

before levelling out in alluvial landscapes in lowlands on either side of the Range.

However, catchments flowing from the plateau have distinctly different characters.


Plate 1: Crest of main Kaimai Range, viewed from eastern side, showing steep faces and landslide scars.

Plate 2: Easy terrain on eastern side of Kaimai Range, with Whakamarama Plateau in background.


Western catchments originate on the crest of the plateau either on the immediate edge

or just above the top of a steep fault scarp (see Plate 3). The streams fall steeply over

a short distance into the Waihou River and then meander over an extensive flood

plain, which follows the downthrown section of crustal rift associated with the

Hauraki fault, into the Firth of Thames. Eastern catchments draining the plateau

initially cross the plateau where they step down over a series of ignimbrite shelves

within heavily-incised gorges, before flowing through generally more evenly-sloping

sections draining hill country around the edge of the Tauranga Basin and Tauranga

Harbour. These waterways drain into Tauranga harbour via short estuarine sections.

3.2 History of land use

Tauranga

Māori burnt extensive areas of lowland vegetation, resulting in the replacement of tall

forest by a mosaic of fernland, shrubland, remnants of primary forest and secondary

forest, and areas under cultivation for kumara and taro. Areas were cultivated on a

rotational basis, through a cycle of burning, then planting and cultivation for several

seasons, then leaving the land to lay fallow (Stokes 1980).

European settlement on a significant scale began on the Tauranga and Te Puke

lowlands in the 1870s and soon extended over open country further inland. The major

clearing of forest in the Whakamarama, Kaimai, and Oropi areas and south-west of

Te Puke had been made by 1900. Clearings in the Whakamarama area were the sites

of settlement during the Hauhau conflict of the 1860s.

Podocarps and tawa were logged in parts of the southern Kaimai from the mid-1920s,

particularly from the foothills. Remnants of tramways used to extract timber dating to

the 1920s and 1930s are present within the Puketoki Reserve, on the north-eastern

edge of the Whakamarama Plateau. Logging had ceased by 1972 (Dale and James

1977).

Virtually all forests on easier terrain have been logged for podocarps and broadleaved

species. Before 1945, only softwoods were felled, but since then some of the more

numerous hardwoods have also been extracted. Logging started about Whakamarama

in the early 1900s, and continued until about 1970, leaving untouched only the forest

above 500 m in the western quarter. Apart from very minor light operations, logging

did not begin on the northern Mamaku Plateau before 1920 where, until 1945, logging

was confined largely to forest on those parts of the plateau within reach of tramways

and steam-driven log haulers. This included felling of red beech (Nothofagus fusca)

for fencing and mining timbers. Over the ensuing 30 years, most of the previously

logged forest was roaded and re-logged, as were many particularly inaccessible areas,

including broken country in the north-west quarter of the Mamaku Plateau and the

western side of the Papamoa Range (Beadel 2006).

Between 1900 and 1920, many blocks were opened and farmed around Ngawaro and

Kaharoa. Although many ventures were initially unsuccessful, many abandoned

farms were re-occupied in the 1950s and 1960s. Much secondary forest was cleared

for farming alongside SH33 in the 1960s.


Plate 3: Steep section of main Kaimai Range, central part of middle Waihou catchment.

Plate 4: Farmland and secondary shrubland extending to crest of main Kaimai Range, in the vicinity of Te Weraiti, northern end of upper Waihou catchment.


Towns were originally established around mission stations and sites selected for

establishment of settlements. The latter was facilitated, in part, by the redistribution

of land confiscated from local Māori after the New Zealand wars (Stokes 1980).

Tauranga has become a major entry and exit point for goods in New Zealand,

particularly timber and timber products, and the growth of the port has been partially

responsible for the growth of Tauranga‘s population, and the geographical expansion

of urban and peri-urban areas (Wildland Consultants 2008).

Conversion of pastoral land to orcharding, primarily avocados and kiwifruit, has seen

significant land use changes over the previous few decades.

Kaimai

Timber extraction commenced in the Ohinemuri and Karangahake areas around 1880

and continued into the 1920s (Dale and James 1977). The Waitawheta valley was the

focus of kauri timber extraction using trip damming, tramways and steam haulers, and

nearly all the accessible kauri has been logged (Dale and James 1977). Logging was

associated with frequent burning of the country surrounding mills.

The discovery of gold at Te Aroha in 1879 led to a gold rush in the Waiorongomai

Valley in 1881. Large capital investment in infrastructure within the valley during the

1880s and 1890s did not pay off as gold yields from the rock proved lower than

anticipated. When capital dried up as a result of the low returns, mining efforts were

abandoned, leaving most of the equipment of infrastructure on-site. In more recent

years, zinc and lead ores have been mined on the slopes of Te Aroha. The Tui Mine

was opened by Norpac Mining Ltd in 1967 to mine copper, lead, and zinc. However,

unacceptable levels of mercury were found in the ore, and for this and other reasons,

Norpac went into liquidation in 1975 and the Tui Mine was abandoned. Remediation

of the toxic tailings dump is currently in progress.

Mamaku

Logging of forests on the Mamaku Plateau began in 1888 with the establishment of

the Steele Brothers mill, just north of the current Mamaku township. The main

species logged was rimu. Logging intensified through the late 1890s, following the

completion of the railway line to Mamaku in 1894 and the construction of tramways

into the surrounding plateau (Beveridge et al. 2009). Forest clearance for farming

began following the establishment of Mamaku township. Logging of cut-over forest

continued until the 1970s when focus of forestry activities shifted to conversion to

pine plantations. Large areas of cut-over forest on the southern side of the Mamaku

plateau were clear-felled and planted in pines. Forest clearance and conversion to

pine continued into the late 1980s.

Foothills and hill country timber industries were operative on the plateau until the late

1970s. Podocarps and tawa were logged in parts of the southern Kaimai from the

mid-1920s. Logging had ceased by 1972 (Dale and James 1977). The Woods Mill

block was logged between 1933 and 1942 (Wills 1994), and forests to the west of

Mokaihaha were logged by the Bartholomew Timber Company of Te Whetu (1905-

76), whose tramway terminated less than half a kilometre from the current boundary

of the Mokaihaha Ecological Area (Smale et al. 1997). The eighty-eight year history


of podocarp logging on the plateau ended in 1976 with the termination of

New Zealand Railways operations in the vicinity of Mokaihaha. Most logged areas

were subsequently clear-felled and replaced by plantations of exotic conifers under

schemes implemented by the New Zealand Forest Service in the late 1970s and early

1980s (Crook 1978; Smale et al. 1997).

Waihou

The settlement of Paeroa township started in 1840, with the arrival of the Thorp

family, and by 1870s the township was being developed. The discovery of gold at

Karangahake in 1869 led to the opening of the Ohinemuri Goldfield on 3 March 1875.

In 1889 the cyanide process was trialled by the New Zealand Crown Mines Company

at Karangahake. This was the first time cyanide extraction had been used on a large

scale for commercial mining. Waihi township developed around the Martha mine,

and when gold production peaked in 1909 the town had a population of 9,000.

The Mining Act 1891 designated rivers in the Hauraki District as ―sludge channels‖

for the transport of mines tailings. This Act gave several mining companies at

Karangahake, Waitekauri, and Waihi licence to dump mining tailings - the talcum-like

residue after the bullion had been extracted-into the Ohinemuri River and its

tributaries. An estimated 100 tons of tailings entered the Ohinemuri each day and it is

estimated that, between 1895 and 1952, the Victoria battery alone dumped 11 million

tones of tailings into the Ohinemuri River. When tailings reached the slow-moving

waters of the Ohinemuri in the flat areas around Paeroa, the sediment settled and built

up the river beds, making the river channel progressively shallower. Major floods in

1904 and 1907 prompted local residents to call for an investigation into the causes of

flooding. A Royal Commission was established in 1910 to investigate the flooding

and to make recommendations on remedies to overcome these disastrous events. The

Commission found fault with the 1895 Act of Parliament, but did not recommend its

repeal, and instead proposed a flood control scheme for the district under the banner

―The Waihou and Ohinemuri Rivers Improvement Scheme‖ (Watton 2006). However,

the scale of the proposed scheme was considered too costly for local landowners to

meet and it was reduced in size. Stopbank construction started in 1912 and continued

until around 1924. The scheme saw stopbanks constructed on both sides of the

Ohinemuri, through Paeroa to its confluence with the Waihou River. The Waihou

River was also stopbanked for some distance above and below Paeroa. However, the

Ohinemuri River continued to silt up until the Mining Act was eventually repealed in

1955 after the Waihi Gold Mining Company‘s Victoria battery at Waikino ceased

operations in 1953 (Watton 2006). Major floods occurred in 1917, 1924, 1936, 1954,

1960, 1964, and again in 1976, with other minor annual floods. The Komata River

stopbanks were breached during the floods of 1960 and 1964. In response the Hauraki

Catchment Board proposed a new scheme, the Waihou Valley Flood Protection and

Erosion Control Scheme for the entire Waihou River catchment, from its mouth at

Thames to the headwaters, in the Mamaku Range (Watton 2006).

The Edmeades family settled and began to farm the land along the Upper Waihou

River in 1938. At this stage the river area was heavily covered with fern and ―titree‖

(manuka), which was cleared for farming.


3.3 Present functions and uses

The ranges and plateau are mostly forest-clad and provide multiple services at local,

regional, and national levels. They provide an important recreation resource for

hunters, walkers, trampers, and school groups, who value the cultural heritage and the

landscape, but also the indigenous plants and animals. Four wheel drivers, motorbike

riders and mountain bikers also value the challenges the terrain offers. The natural

heritage of the Kaimai-Mamaku Ranges includes rare vegetation types and vegetation

associations, many rare and threatened taxa, including numerous threatened plants,

North Island brown kiwi, kokako, short tailed bat, Hochstetter‘s frog, Te Aroha stag

beetle, striped skink and kereru. Kereru was historically the subject of cultural

harvest. Today cultural and recreational harvest in the ranges and plateaus centres on

the deer and pigs that are popular with recreational hunters. The ranges also harbour

pest plants and animals, including goats, deer, possums, stoats, and rats, and these

pose a serious threat to indigenous wildlife. The ranges are also a repository of

historical artefacts, including earthworks, structures, and implements associated with

historical timber and mining industries and their associated railway and tramway

infrastructure. Foothills and plateaus have agriculture and exotic plantation forest

intermixed with indigenous forests, with large areas of horticulture, primarily avocado

and kiwifruit. Some of the high points on the Kaimai Range have

telecommunications infrastructure, including T.V. aerials and radio transmitters. One

river has hydro-electric power generation infrastructure. The ranges play an important

role in maintaining water quality for water supply. The ranges also play an important

role in the hydrology of the catchments of the Waihou and Tauranga Harbour, as the

indigenous forest cover helps to reduce peak flows and buffer streambanks from flood

events. Management to promote a healthy forest cover will maintain and enhance this

role, reduce sedimentation and improve water quality, as well as have positive

outcomes for indigenous biodiversity and the experience of visitors.

4. OVERVIEW AND CONTEXT

4.1 Land tenure and status

The Kaimai Range has had a long history of strong public interest, having previously

been the subject of a campaign to establish a National Park in this area. The

Kaimai-Mamaku Forest Park was initially established for soil and water conservation

purposes. Although a large area of the forest-covered ranges is in public ownership,

there are also significant areas of indigenous forest along the foothills in private

ownership, which have significant soil and water functions as well as biodiversity

values.

The Kaimai-Mamaku part of the Waihou River catchment encompasses 118,426 ha,

75% of which is in private ownership. The Waihou catchment is primarily a

developed landscape, with primary land uses for dairy and beef farming, with some

exotic plantation forest in upper catchments.

The Tauranga Basin catchments encompass 122,340 ha, 73% of which is in private

ownership. Land holdings within the Tauranga Basin are generally smaller than those

in the Waihou, there being more lifestyle blocks and orchards, and fewer dairy farms.

state of the environment assessment for the … · mamaku ranges, including all relevant data held...

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